In recent years, in a solid-state imaging device such as a CCD or a CMOS image sensor, a device type has been proposed that uses a photoelectric conversion element that has a photoelectric conversion layer including an organic semiconductor (for example, see PTLs 1 to 5). Such a photoelectric conversion element with use of the organic semiconductor eliminates the necessity for a color filter, allowing a structure and a manufacturing process to be more simplified in comparison with a photoelectric conversion element with use of an inorganic semiconductor.
In the photoelectric conversion element described in each of PTLs 1 to 3, a lower electrode, a photoelectric conversion layer including the organic semiconductor, and an upper electrode are stacked in this order on a substrate. It is to be noted that, in some cases, a variety of intermediate layers such as an electron blocking layer, a buffer layer, and an active layer may be also provided between the photoelectric conversion layer and each of the electrodes.